The invention pertains to a rotatable cutting tool that is useful for the impingement of earth strata such as, for example, asphaltic roadway material, coal deposits, mineral formations and the like. More specifically, the present invention pertains to a rotatable cutting tool that is useful for the impingement of earth strata wherein the cutting tool body possesses improved design so as to provide for improved performance characteristics for the rotatable cutting tool.
Rotatable cutting tools have been used to impinge earth strata such as, for example, asphaltic roadway material or ore bearing or coal bearing earth formations or the like. Generally speaking, these kinds of rotatable cutting tools have an elongate cutting tool body typically made from steel and a hard tip (or insert) affixed to the cutting tool body at the axial forward end thereof. The hard tip is typically made from a hard material such as, for example, cemented (cobalt) tungsten carbide. The rotatable cutting tool is rotatably retained or held in the bore of a tool holder or, in the alternative, in the bore of a sleeve that is in turn held in the bore of a holder.
The holder is affixed to a driven member such as, for example, a driven drum of a road planing machine. In some designs, the driven member (e.g., drum) carries hundreds of holders wherein each holder carries a rotatable cutting tool. Hence, the driven member may carry hundreds of rotatable cutting tools. The driven member is driven (e.g., rotated) in such a fashion so that the hard tip of each one of the rotatable cutting tools impinges or impacts the earth strata (e.g., asphaltic roadway material) thereby fracturing and breaking up the material into debris.
As can be appreciated, during operation the rotatable cutting tool and the cutting insert are typically subjected to a variety of extreme cutting forces and stresses in an abrasive and erosive environment. In addition, during a machining operation the cutting insert becomes heated. The heat spreads quickly through the cutting insert. The cutting insert reaches, in a very short time, a range of temperatures within which the resistance to plastic deformation of the cutting insert material decreases. When large cutting forces act on the cutting insert, this phenomenon entails a risk that the cutting insert will be subject to plastic deformation, in particular, in the proximity of the cutting edge, where insert breakage can result. In order to diminish the risk of plastic deformation, an efficient system for cooling the cutting insert would be desirable, whereby the working temperature of the insert can be regulated within desired limits.
As is also known during use of the rotatable cutting tool, a substantial amount of dust may be generated, e.g. coal dust during a mining operation. When the dust becomes air borne, it becomes a risk for humans and equipment in the immediate area. For example, the dust can be inhaled by humans (health risk) or the dust can be ignited by mining activities causing an explosion (safety risk). In order to reduce or minimize health and/or safety risks, an efficient system that reduces or minimizes the amount of dust that is generated would be desirable.
The present invention has been developed in view of the foregoing.